CORRESPONDENCE, 1846-55. 209 



To Sir John Herschel. 



41 Chalcot Villas, March 26, 1850. 



MY DEAE SIR JOHN, I never heard the polar axis approxima- 1850. 

 tion. Pray throw it out in type, for it is quite a fanny thing 

 that we beat the French after all. And the polar axis is the 

 only sensible diameter the earth has got. He keeps snug and 

 quiet, and lets all the others spin about him. I think a dialogue 

 might be written between the polar axis and an equatorial 

 diameter quiescence against restlessness. 



And so Logical systems are bothersome. I have got sixty- 

 four more syllogisms symbolised, in which terms take quantity 

 from others. As 



For every Z there is an X, which is not Y. 

 Some Y's are Z's. 



Required the inference. 



Symbol ('((). 

 Inference (. ( . 

 Some X's are not Z's. 



These are really h ard. To give an instance. 



' To say nothing of those who succeeded by effort, there were 

 some who owed all to fortune, for they gained the end without 

 any attempt whatever, if indeed it be not more correct to say 

 that the end gained them. But for every one who was successful 

 with or without effort, at least one could be pointed out who 

 began, but abandoned the trial before the result was declared. 

 And yet so strangely is desert rewarded in this world, there was 

 not one of these faint-hearted men but was as fortunate as any 

 of those who used their best endeavours.' 



I will answer for it that if this were presented to any writer 

 on logic without warning, he would pass it over as not self- 

 contradictory at least. But for all that, it contains the same 

 error as the following : ' All men are animals, and some are 

 not.' 



Yours very truly, 



A. DE MORGAN. 



To the Rev. Dr. Whewell. 



7 Camden Street, May 25, 1850. 



MY DEAR SIR, I am much obliged to you for the continuation 

 of the chain of events. I see you are propagating an undulation 



P 



